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Looking for a Comet and Finding... a Grizzly?

AJAX manipulates the local representation
of a Web page using
JavaScript and updates it with
content (usually XML or JSON) that is fetched dynamically using HTTP.
AJAX is becoming very popular because it avoids page refreshes
and provides a more dynamic interface but
one of its challenges is how to avoid stale data;
there are a number of techniques to address this, including
polling,
piggybacking and
long-lived HTTP connections.

These approaches have been around for a while in one way or another
but, like AJAX, are becoming more popular and are being given different names.
For example, the collection of technologies is called
Reverse AJAX
in DWR 2.0
(blog,
Intro@Prokata).
And the usef of long-lived HTTP connections,
also called
HTTP Streaming
is also called
Comet.

One of the interesting developments is that the
Grizzly's machinery provides a very good foundation for Comet -- see for example the report from
AgileAjax,
and Jean-Francois and others are talking about using it more widely in that direction.
I hope this will make it into one of our future releases of
GlassFish.